<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/infiniband, branch v3.4.76</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>IB/ipath: Convert ipath_user_sdma_pin_pages() to use get_user_pages_fast()</title>
<updated>2013-12-04T18:50:28+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2013-10-04T13:29:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ac6638ed78e168e6c6c77e5ac6d9a6c4f49d0040'/>
<id>ac6638ed78e168e6c6c77e5ac6d9a6c4f49d0040</id>
<content type='text'>
commit 4adcf7fb6783e354aab38824d803fa8c4f8e8a27 upstream.

ipath_user_sdma_queue_pkts() gets called with mmap_sem held for
writing.  Except for get_user_pages() deep down in
ipath_user_sdma_pin_pages() we don't seem to need mmap_sem at all.

Even more interestingly the function ipath_user_sdma_queue_pkts() (and
also ipath_user_sdma_coalesce() called somewhat later) call
copy_from_user() which can hit a page fault and we deadlock on trying
to get mmap_sem when handling that fault.  So just make
ipath_user_sdma_pin_pages() use get_user_pages_fast() and leave
mmap_sem locking for mm.

This deadlock has actually been observed in the wild when the node
is under memory pressure.

Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Mike Marciniszyn &lt;mike.marciniszyn@intel.com&gt;
[ Merged in fix for call to get_user_pages_fast from Tetsuo Handa
  &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;.  - Roland ]
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 4adcf7fb6783e354aab38824d803fa8c4f8e8a27 upstream.

ipath_user_sdma_queue_pkts() gets called with mmap_sem held for
writing.  Except for get_user_pages() deep down in
ipath_user_sdma_pin_pages() we don't seem to need mmap_sem at all.

Even more interestingly the function ipath_user_sdma_queue_pkts() (and
also ipath_user_sdma_coalesce() called somewhat later) call
copy_from_user() which can hit a page fault and we deadlock on trying
to get mmap_sem when handling that fault.  So just make
ipath_user_sdma_pin_pages() use get_user_pages_fast() and leave
mmap_sem locking for mm.

This deadlock has actually been observed in the wild when the node
is under memory pressure.

Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Mike Marciniszyn &lt;mike.marciniszyn@intel.com&gt;
[ Merged in fix for call to get_user_pages_fast from Tetsuo Handa
  &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;.  - Roland ]
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ib_srpt: always set response for task management</title>
<updated>2013-10-13T22:42:49+00:00</updated>
<author>
<name>Jack Wang</name>
<email>jinpu.wang@profitbricks.com</email>
</author>
<published>2013-09-30T08:09:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a2a88da3923e86a39755ae02737ba0af1ddae121'/>
<id>a2a88da3923e86a39755ae02737ba0af1ddae121</id>
<content type='text'>
commit c807f64340932e19f0d2ac9b30c8381e1f60663a upstream.

The SRP specification requires:

  "Response data shall be provided in any SRP_RSP response that is sent in
   response to an SRP_TSK_MGMT request (see 6.7). The information in the
   RSP_CODE field (see table 24) shall indicate the completion status of
   the task management function."

So fix this to avoid the SRP initiator interprets task management functions
that succeeded as failed.

Signed-off-by: Jack Wang &lt;jinpu.wang@profitbricks.com&gt;
Signed-off-by: Nicholas Bellinger &lt;nab@linux-iscsi.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c807f64340932e19f0d2ac9b30c8381e1f60663a upstream.

The SRP specification requires:

  "Response data shall be provided in any SRP_RSP response that is sent in
   response to an SRP_TSK_MGMT request (see 6.7). The information in the
   RSP_CODE field (see table 24) shall indicate the completion status of
   the task management function."

So fix this to avoid the SRP initiator interprets task management functions
that succeeded as failed.

Signed-off-by: Jack Wang &lt;jinpu.wang@profitbricks.com&gt;
Signed-off-by: Nicholas Bellinger &lt;nab@linux-iscsi.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ib_srpt: Destroy cm_id before destroying QP.</title>
<updated>2013-10-13T22:42:49+00:00</updated>
<author>
<name>Nicholas Bellinger</name>
<email>nab@linux-iscsi.org</email>
</author>
<published>2013-09-18T19:48:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d08417dc4350604a5f8be7c144cb67a9f1bab806'/>
<id>d08417dc4350604a5f8be7c144cb67a9f1bab806</id>
<content type='text'>
commit 0b41d6ca616ddeb3b6c0a80e8770b6f53cd42806 upstream.

This patch fixes a bug where ib_destroy_cm_id() was incorrectly being called
after srpt_destroy_ch_ib() had destroyed the active QP.

This would result in the following failed SRP_LOGIN_REQ messages:

Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff1762bd, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c903009f8f41)
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff1758f9, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 2 (guid=0xfe80000000000000:0x2c903009f8f42)
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff175941, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 2 (guid=0xfe80000000000000:0x2c90300a3cfb2)
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff176299, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c90300a3cfb1)
mlx4_core 0000:84:00.0: command 0x19 failed: fw status = 0x9
rejected SRP_LOGIN_REQ because creating a new RDMA channel failed.
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff176299, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c90300a3cfb1)
mlx4_core 0000:84:00.0: command 0x19 failed: fw status = 0x9
rejected SRP_LOGIN_REQ because creating a new RDMA channel failed.
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff176299, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c90300a3cfb1)

Reported-by: Navin Ahuja &lt;navin.ahuja@saratoga-speed.com&gt;
Signed-off-by: Nicholas Bellinger &lt;nab@linux-iscsi.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 0b41d6ca616ddeb3b6c0a80e8770b6f53cd42806 upstream.

This patch fixes a bug where ib_destroy_cm_id() was incorrectly being called
after srpt_destroy_ch_ib() had destroyed the active QP.

This would result in the following failed SRP_LOGIN_REQ messages:

Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff1762bd, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c903009f8f41)
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff1758f9, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 2 (guid=0xfe80000000000000:0x2c903009f8f42)
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff175941, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 2 (guid=0xfe80000000000000:0x2c90300a3cfb2)
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff176299, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c90300a3cfb1)
mlx4_core 0000:84:00.0: command 0x19 failed: fw status = 0x9
rejected SRP_LOGIN_REQ because creating a new RDMA channel failed.
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff176299, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c90300a3cfb1)
mlx4_core 0000:84:00.0: command 0x19 failed: fw status = 0x9
rejected SRP_LOGIN_REQ because creating a new RDMA channel failed.
Received SRP_LOGIN_REQ with i_port_id 0x0:0x2590ffff176299, t_port_id 0x2c903009f8f40:0x2c903009f8f40 and it_iu_len 260 on port 1 (guid=0xfe80000000000000:0x2c90300a3cfb1)

Reported-by: Navin Ahuja &lt;navin.ahuja@saratoga-speed.com&gt;
Signed-off-by: Nicholas Bellinger &lt;nab@linux-iscsi.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>IPoIB: Fix send lockup due to missed TX completion</title>
<updated>2013-03-28T19:12:25+00:00</updated>
<author>
<name>Mike Marciniszyn</name>
<email>mike.marciniszyn@intel.com</email>
</author>
<published>2013-02-26T15:46:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3d2e7424b3e18dc851a4b0efdc6676c09573f55f'/>
<id>3d2e7424b3e18dc851a4b0efdc6676c09573f55f</id>
<content type='text'>
commit 1ee9e2aa7b31427303466776f455d43e5e3c9275 upstream.

Commit f0dc117abdfa ("IPoIB: Fix TX queue lockup with mixed UD/CM
traffic") attempts to solve an issue where unprocessed UD send
completions can deadlock the netdev.

The patch doesn't fully resolve the issue because if more than half
the tx_outstanding's were UD and all of the destinations are RC
reachable, arming the CQ doesn't solve the issue.

This patch uses the IB_CQ_REPORT_MISSED_EVENTS on the
ib_req_notify_cq().  If the rc is above 0, the UD send cq completion
callback is called directly to re-arm the send completion timer.

This issue is seen in very large parallel filesystem deployments
and the patch has been shown to correct the issue.

Reviewed-by: Dean Luick &lt;dean.luick@intel.com&gt;
Signed-off-by: Mike Marciniszyn &lt;mike.marciniszyn@intel.com&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 1ee9e2aa7b31427303466776f455d43e5e3c9275 upstream.

Commit f0dc117abdfa ("IPoIB: Fix TX queue lockup with mixed UD/CM
traffic") attempts to solve an issue where unprocessed UD send
completions can deadlock the netdev.

The patch doesn't fully resolve the issue because if more than half
the tx_outstanding's were UD and all of the destinations are RC
reachable, arming the CQ doesn't solve the issue.

This patch uses the IB_CQ_REPORT_MISSED_EVENTS on the
ib_req_notify_cq().  If the rc is above 0, the UD send cq completion
callback is called directly to re-arm the send completion timer.

This issue is seen in very large parallel filesystem deployments
and the patch has been shown to correct the issue.

Reviewed-by: Dean Luick &lt;dean.luick@intel.com&gt;
Signed-off-by: Mike Marciniszyn &lt;mike.marciniszyn@intel.com&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>RDMA/nes: Fix for terminate timer crash</title>
<updated>2013-01-17T16:50:51+00:00</updated>
<author>
<name>Tatyana Nikolova</name>
<email>Tatyana.E.Nikolova@intel.com</email>
</author>
<published>2012-12-06T19:58:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0d38a8789caf511e5b997caf76eb32fddbff051c'/>
<id>0d38a8789caf511e5b997caf76eb32fddbff051c</id>
<content type='text'>
commit 7bfcfa51c35cdd2d37e0d70fc11790642dd11fb3 upstream.

The terminate timer needs to be initialized just once.

Signed-off-by: Tatyana Nikolova &lt;Tatyana.E.Nikolova@intel.com&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: CAI Qian &lt;caiqian@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 7bfcfa51c35cdd2d37e0d70fc11790642dd11fb3 upstream.

The terminate timer needs to be initialized just once.

Signed-off-by: Tatyana Nikolova &lt;Tatyana.E.Nikolova@intel.com&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: CAI Qian &lt;caiqian@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>RDMA/nes: Fix for crash when registering zero length MR for CQ</title>
<updated>2013-01-17T16:50:51+00:00</updated>
<author>
<name>Tatyana Nikolova</name>
<email>Tatyana.E.Nikolova@intel.com</email>
</author>
<published>2012-12-06T20:05:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e5ca2896f817ef43802387ae2f41a9c70e30ee86'/>
<id>e5ca2896f817ef43802387ae2f41a9c70e30ee86</id>
<content type='text'>
commit 7d9c199a55200c9b9fcad08e150470d02fb385be upstream.

Signed-off-by: Tatyana Nikolova &lt;Tatyana.E.Nikolova@intel.com&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: CAI Qian &lt;caiqian@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 7d9c199a55200c9b9fcad08e150470d02fb385be upstream.

Signed-off-by: Tatyana Nikolova &lt;Tatyana.E.Nikolova@intel.com&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: CAI Qian &lt;caiqian@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>infiniband: pass rdma_cm module to netlink_dump_start</title>
<updated>2012-10-28T17:14:15+00:00</updated>
<author>
<name>Gao feng</name>
<email>gaofeng@cn.fujitsu.com</email>
</author>
<published>2012-10-04T20:15:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6114941a295ff186d29ab7462cce6a41a089c354'/>
<id>6114941a295ff186d29ab7462cce6a41a089c354</id>
<content type='text'>
[ Upstream commit 809d5fc9bf6589276a12bd4fd611e4c7ff9940c3 ]

set netlink_dump_control.module to avoid panic.

Signed-off-by: Gao feng &lt;gaofeng@cn.fujitsu.com&gt;
Cc: Roland Dreier &lt;roland@kernel.org&gt;
Cc: Sean Hefty &lt;sean.hefty@intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 809d5fc9bf6589276a12bd4fd611e4c7ff9940c3 ]

set netlink_dump_control.module to avoid panic.

Signed-off-by: Gao feng &lt;gaofeng@cn.fujitsu.com&gt;
Cc: Roland Dreier &lt;roland@kernel.org&gt;
Cc: Sean Hefty &lt;sean.hefty@intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>IB/srp: Avoid having aborted requests hang</title>
<updated>2012-10-07T15:32:29+00:00</updated>
<author>
<name>Bart Van Assche</name>
<email>bvanassche@acm.org</email>
</author>
<published>2012-08-24T10:29:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=22fb582405002812d8fb89d0ed1264e97d3d25ad'/>
<id>22fb582405002812d8fb89d0ed1264e97d3d25ad</id>
<content type='text'>
commit d8536670916a685df116b5c2cb256573fd25e4e3 upstream.

We need to call scsi_done() for commands after we abort them.

Signed-off-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Acked-by: David Dillow &lt;dillowda@ornl.gov&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit d8536670916a685df116b5c2cb256573fd25e4e3 upstream.

We need to call scsi_done() for commands after we abort them.

Signed-off-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Acked-by: David Dillow &lt;dillowda@ornl.gov&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>IB/srp: Fix use-after-free in srp_reset_req()</title>
<updated>2012-10-07T15:32:29+00:00</updated>
<author>
<name>Bart Van Assche</name>
<email>bvanassche@acm.org</email>
</author>
<published>2012-08-24T10:27:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0e4765fd9c0f8df577e0b8cbea927c2051710f27'/>
<id>0e4765fd9c0f8df577e0b8cbea927c2051710f27</id>
<content type='text'>
commit 9b796d06d5d1b1e85ae2316a283ea11dd739ef96 upstream.

srp_free_req() uses the scsi_cmnd structure contents to unmap
buffers, so we must invoke srp_free_req() before we release
ownership of that structure.

Signed-off-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Acked-by: David Dillow &lt;dillowda@ornl.gov&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 9b796d06d5d1b1e85ae2316a283ea11dd739ef96 upstream.

srp_free_req() uses the scsi_cmnd structure contents to unmap
buffers, so we must invoke srp_free_req() before we release
ownership of that structure.

Signed-off-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Acked-by: David Dillow &lt;dillowda@ornl.gov&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>IPoIB: Fix use-after-free of multicast object</title>
<updated>2012-10-07T15:32:28+00:00</updated>
<author>
<name>Patrick McHardy</name>
<email>kaber@trash.net</email>
</author>
<published>2012-08-30T07:01:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=350f3edb0a05c340853c75f4c5007a72ebd9e32f'/>
<id>350f3edb0a05c340853c75f4c5007a72ebd9e32f</id>
<content type='text'>
commit bea1e22df494a729978e7f2c54f7bda328f74bc3 upstream.

Fix a crash in ipoib_mcast_join_task().  (with help from Or Gerlitz)

Commit c8c2afe360b7 ("IPoIB: Use rtnl lock/unlock when changing device
flags") added a call to rtnl_lock() in ipoib_mcast_join_task(), which
is run from the ipoib_workqueue, and hence the workqueue can't be
flushed from the context of ipoib_stop().

In the current code, ipoib_stop() (which doesn't flush the workqueue)
calls ipoib_mcast_dev_flush(), which goes and deletes all the
multicast entries.  This takes place without any synchronization with
a possible running instance of ipoib_mcast_join_task() for the same
ipoib device, leading to a crash due to NULL pointer dereference.

Fix this by making sure that the workqueue is flushed before
ipoib_mcast_dev_flush() is called.  To make that possible, we move the
RTNL-lock wrapped code to ipoib_mcast_join_finish().

Signed-off-by: Patrick McHardy &lt;kaber@trash.net&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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commit bea1e22df494a729978e7f2c54f7bda328f74bc3 upstream.

Fix a crash in ipoib_mcast_join_task().  (with help from Or Gerlitz)

Commit c8c2afe360b7 ("IPoIB: Use rtnl lock/unlock when changing device
flags") added a call to rtnl_lock() in ipoib_mcast_join_task(), which
is run from the ipoib_workqueue, and hence the workqueue can't be
flushed from the context of ipoib_stop().

In the current code, ipoib_stop() (which doesn't flush the workqueue)
calls ipoib_mcast_dev_flush(), which goes and deletes all the
multicast entries.  This takes place without any synchronization with
a possible running instance of ipoib_mcast_join_task() for the same
ipoib device, leading to a crash due to NULL pointer dereference.

Fix this by making sure that the workqueue is flushed before
ipoib_mcast_dev_flush() is called.  To make that possible, we move the
RTNL-lock wrapped code to ipoib_mcast_join_finish().

Signed-off-by: Patrick McHardy &lt;kaber@trash.net&gt;
Signed-off-by: Roland Dreier &lt;roland@purestorage.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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